Figure REF  shows the first of the two interesting observations we want to discuss:
a seemingly universal pattern in the shapes of the \(p_{\rm T}\)  distributions of all prompt quarkonia.
Indeed, when presented as \(p_{\rm T}/M\)  distributions,
where \(M\)  is the mass of the quarkonium state,
the prompt \({\rm J}/\psi \) , \(\chi _{c1}\) , \(\chi _{c2}\) , \(\psi {\rm (2S)}\)  and \(\Upsilon {\rm (nS)}\)  production cross sections
are all compatible with a single kinematic dependence,
at least for mid-rapidity (\(|y| \lesssim 1\) ) and for not-too-small \(p_{\rm T}/M\) .
This observation confirms, with higher-\(p_{\rm T}\)  data, a trend first noticed in Ref. [1]}.
The consistency of the \(p_{\rm T}/M\)  distributions is quantified in Section ,
while Ref. [2]} offers a detailed evaluation of
how precisely the current cross section measurements constrain
the \(\chi _{c}\)  \(p_{\rm T}/M\)  trend to be similar to those of the \({\rm J}/\psi \)  and \(\psi {\rm (2S)}\) .
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